Uncovered troops or protected in trenches, concrete bunkers or wooden huts, deep dugouts, ammunition stocks, ships, armoured fortresses or houses, tanks or planes, the destruction of each type of target often requires a specific type of projectile. And when used for making war, the human's imagination can be sometimes particularly prolific...

Hollow projectiles, named 'shells', still spherical and filled with inflammable material or gunpowder, appeared in the 17th century. The delayed ignition of the inner explosive charge induced the development of a new device, called 'fuze', that was only a wood cylinder inserted through the shell wall in an hole ('eye'), and filled by compacted slow-burning gunpowder that was ignited by the hot gasses inside the gun tube at the projectile discharge.

Another important evolution appeared in 1803 when the British officer Shrapnell invented a spherical hollow shell filled with gunpowder and steel bullets, whose explosion spread on the uncovered enemy soldiers a deadly cloud of balls.

The 19th century saw a rapid acceleration of the artillery techniques development, with guns progressively becoming more powerful, more accurate, with higher rate of fire and longer ranges. These weapons evolutions created the need of adapted ammunitions, that will evoluate from the initial spherical shape to the incomparably more sophisticated projectiles of the Great War.

The following highlights might serve as a tentative summary of this evolution :

The shell stability on its trajectory is highly improved by the gyroscopic effect bring by the shell spin, providing incomparably better accuracy and range.

This shell spin was obtaned thanks to helicoïdal grooves machined inside the barrel of the gun ('rifling').

The projectiles had to adapt and changed their shape to a oblong and ogival profile instead of the usual sphere, and are equipped with rotation pins, lead lining or a copper driving band, designed to match or indent in the tube grooves and give the spin to the expulsed projectile.

The seek of higher rates of fire soon imposed to substitute the muzzle loading process that needed to modify the gun aiming between each shot, by a tube bottom loading process through an opening mechanism named 'breech'.

The gunpowder propelling charge is also introduced by the gun breech just after the shell, in pre-weighed containers in tissue named 'cartridge bags' or metal named 'cartridges cases', separated or assembled with the shell.

The usual competition between the sword and the armor induced several developments of the expolsive compositions inside the shells, with increasingly powerful effects and controlled burst sequence, as well as the apparition of specialised projectiles and weapons adapted to specific targets (armors, earthworks, uncovered troops, etc...).

Once again the artillery projectiles had to evoluate with various designs and the introduction of numerous increasingly sophisticated fuzes.

grains or chords of a nitrocellulose / nitroglycerine compound - in english 'cordite'.

It could be conditioned either :

packed in pre-weighted tissue bags ("cartridge bags"). It was therefore possible to adapt the propelling charge to the needed range, by cha,ging the number or type of bags.

packed into metal cartridge cases (copper or brass, more rarely steel). The propelling charge was then constant, but this disadvantage was largely offset by the easier handling allowing higher fire rates.

Scheme of a German 7.7cm fieldgun complete ammunition

Scheme of a German 10.5 cm howitzer shell cartridge case

There were different techniques for the assembly of the shell and the propelling charge :

fixed : the metal (copper, brass and sometimes steel, aluminium, ...) cartridge case containing the invariant propelling charge is crimped on the shell, and this assembly is handled as a single item, allowing higher fire rates.

semi-fixed : the cartrigge and the shell are handled separately, and gathered at fire time. The weight of the propelling charge can be lowered before the discharge according to the fire officer calculations. This was useful with high angle weapons such as mortars or howitzers.

separated : the propelling charge bags are introduced after the shell by the gun breech, and the last one is often contained inside a short metal case including the starter. In this last cas, the propelling charge can be very easily modified.

From the left to the right, German 7.6cm light Minenwerfer shell, German 7.7cm fieldgun high explosive shell, German 7.7cm fieldgun shrapnell shell, French 75mm fieldgun high explosive shell, French 75mm fieldgun shrapnell shell, German 10.5cm howitzer cartridge case (separated propelling charge).

When the propelling charge was contained into a cartridge case, its ignition was triggered by an integrated primer filled with a high sensitive material (for instance mercury fulminate). It was located at the cartridge base, and was triggered machanically (hammered) or electrically by the means of a system located inside the gun's breech.

The propelling charges that was contained in bags or not conditioned required the use of a friction, percussion or electrical primer tube, inserted through the gun base or the breech.

All the 1914 propelling charges used cordite or smokeless gunpowder, more adaped to stealth. Some propelling material were more stable and required an intermediate igniter charge (for instance gunpowder) to burst them.

Friction primer tubes for German minenwerfers

Base of a German 7.7cm fieldgun ammunition, manufactured by the Fabrique Nationale de Herstal in invaded Belgium (November 1917) - See the primer cap at the center..

The shell inflight stability was insured by its spin movement around its axis (gyroscopic effect, well known by scientists). This spin was given to the projectile when fired, by a system of helicoïdal grooves machined inside the gun barrel ('rifling') in which shell's soft metal rotation pins or indents made on soft metal circle(s) were inserted, driving the projectile out of the tube.

This principle knew severeal developments during the second half of the XIXth century, but two major methods existed in 1914, both based on the 'driving band' technique :

In most cases, for breech-loading guns, the shell base (and sometimes body) was circled by one or several soft metal or copper driving bands, with an external diameter equal to the barrel inner diameter at the bottom of the rifling grooves. When introduced inside the gun's rear chamber, the shell was forced inside the rifled tube section, and the barrel helicoïdal grooves pressed inclined indents into the driving bands. When expulsed by the propelling charge, the shell followed the movement of its driving bands locked inside the rifling grooves, giving it the desired spin movement that it kept during its flight afterwards.

In more rare cases of rifled muzzle-loading guns (particularly the German minenwerfers lMW, mMW and sMW), the gun had less and larger grooves, and the les rayures du canon étaient moins nombreuses, and the corresponding inclined indents were pre-machined in the projectiles driving bands. At the contrary of the previous case, the existence of indents inside the driving bands of such projectiles does not mean that they have been fired, when observed nowadays...

Myriads of fragments of these copper driving bands can still be found on former WW1 battlefields today.

15cm sFH02 German howitzer tube rifling

120mm German shrapnell shell equipped with 4 driving bands

Wartime scheme showing the forcing of the shell's driving band into the rifled section grooves.

The nature of the shells explosive fillings was also subject to a constant evolution. The initial times gun powder, that could easily be exploded by a blow or even friction was not poweful enough and used to braek shells into too big fragments that would not fly far and quick enough. It was still in use in WW1 but only with very old guns and ammunition, or in fuzes.

This material was then progressively replaced by derivated products of the Nitroglycerine, primal componebt of the well-jnown dynamite, and more particularly the Trinitrotoluene (TNT). This material acts by detonating rather than exploding. The detonation is a much more powerful reaction than the explosion, that is a surface reaction progressively progressing inside the explosive material layer by layer, while the detonation bursts the whole mass almost instantaneously. But if the breaking power of TNT was much higher, it was a difficult material to burst.

A 'miracle' material was then invented, alloying a great detonating power and ease. The picric acid, named 'Mélinite' in France, and 'Lyddite' in England, or 'Granatfüllung 88' in Germany, was used. However, this material manufacturing was hazardous, and it was so instable that it needed the shells inside walls to be varnished or tinned, since it was reacting with steel and formed highly unstable picrate salts that could burst the detonation only under the action of the shell acceleration in the gun barrel... !

This is how the armies came back to explosives giving a better compromise between power and stability, but needing to add to the fuzes a powerful exploder sometimes called gaine (for instance using powder picric acid), itself burst by a smaller fulminate of mercury detonator triggered directly by the fuze.

French typical pyrotechnic chain for detonation of high-explosive 75mm shells loaded with melinite, including (from the left to the right) a percussion fuze Nr 24/31, a thread adaptator, a 2-grams fulminate of mercury detonator, and an exploder (sometimes calles gaine) filled with powder picric acid.

Several explosives were used by the fighting nations during WW1, including :

German name

French name

British name

Type of explosive

Power

Stability

Remarks

SchiessPulver

Poudre noire

Gunpowder

Exploding

Moderate

Inflammable, explodes under a flame, a primer or a spark action.

Used in artifices, fuzes pyrotechnics, and in old explosive shells. Different variants in granulometry and composition.

Fulminate de mercure

Fulminate of mercury

Detonating

Very high

Highly unstable, detonates on shocks, friction or heat.

Produces a violent flash but not hot and long enough to burst gunpowder or a stable explosive. Used as a primer or a detonator in shells, but usually in association with an unstable explosive filled exploder (or gaine).

Nitroglycérine

Nitroglycerine

Detonating

Very high

Highly unstable, detonates on shocks, blows, heat or even by sun decomposition into even more unstable components.

Used for manufacturing of more stable explosives and propellants.

Granatfüllung 88

Acide Picrique or Mélinite

Picric Acid or Lyddite (fondu)

Detonating

Very high

Unstable. Detonates under the action of a blow, a primer or a spark. Forms an very unstable and self-detonating picrate salts when in contact with metals.

Usual use in expolders ('gaines'), or in shells (molten condition) in association with an exploder.

Füllpulver 02

Tolite or TNT

Trinitrotoluene or Trotyl (TNT)

Detonating

High, slightly lower than picric acid

Stable, cannot detonate under the action of a flame nor thye heat or a chemical reaction with metals. Needs a direct and powerful hit to detonate, or a detonator (f.i. fulminate of mercury)

Fragmentation shells were still used with the old 80, 90, 95, 120 and 155mm de Bange guns as late as 1916. Made of a thick steel base in which hemispheric rooms were machined for bullets, on which were piled a series of prefragmented honeycombed cast iron waffles and lead bullets, with a hollow head on top containing the burst charge linked to the time fuze, and contained into a thin steel plate cylinder crimped around the base and the head.

The shock of discharge fragmented the cast iron waffles, and the shell burst during the flight dislocated the thin steel enveloppe, spreading the thin cast iron fragments and the lead bullets in all directions but in relatively small numbers, with a moderate speed, and producing a hardly visible burst cloud. Despite these drawbacks, the good compacity of this kind of shell was a real asset, and made of it an efficient ammunition as well for the destruction of common shelters (wood, brick, ...), just by its momentum and mass.

Base of a French 120mm fragmentation shell, with the honeycomb machining for bullets and filled with lead bullets, and view on the hollow bottom of a similar 90mm French fragmentation shell base

Rear charge shrapnel shells were organized a bit like flying guns. The same design was used by all the fighting countries. For instance, in the case of the French 75mm shrapnel shell (7.240 kg), the base and cylindrical body was made of hot formed steel in one piece. The base had thicker walls than the cylindric section ones, and formed a chamber that received the rear burst charge (gunpowder - 100g).

This rear chamber was closed by an inner steel lower diaphragm on top of which were placed the 250 antimony hardened lead bullets, prisoner of a special resin ('collophane') for a good compacity and fixity. An upper steel diaphragm closed the cylinder, on which the fuze-bearing steel head was thread. A low alloy steel tube was passing through the body along its central axis, allowing the shell base gunpowder chamber to communicate with the fuze tail (inserted in the tube by means of a funnel called 'tulip').

In flight, when the fuze ordered the shell explosion, the inner tube let the fuze tail flame communicate with the rear charge. This latter bursted and violently pushed the lower diaphragm forward, propulsing the bullets in the same direction and ejecting the upper diaphragm and the shell head. The lead bullets rain was forming a cone and the impacted gound zone was therefore ellipoïdal, up to 300m long and 25m wide (see the scheme below).

The in-flight shell burst produced a visible cloud thanks to the resin combustion, allowing the gunner to adjust the aiming and range for the next shots.

Usual and almost sole ammunition of the field artillery in 1914, but not adapted to the positions war with entrenched enemy, the shrapnel shells were progressively replaced with high explosive shells with dedicated fuzes. They disappeared compltely from the arsenals between WW1 and WW2.

Base (gunpowder chamber) of the German 7.7cm shrapnel shell, broken at the place where the walls thickness reduces. Found in Artois.

Wartime scheme of the French 75mm fieldgun rear charge shrapnel shell

Head of a German 10.5mm shrapnell shell found in Champagne. One can see the bullets still glued into the collophane resin, and in the center the rest of the tulip.

The time fuze triggers the inflight shell burst, the rear charge propulses the lead bullets forward, so they hit an elliptic area on the ground in front of the trajectory. Used as a antipersonnel weapon on a wide area, but almost unefficient when the enemy is deep entrenched.

Canister shots (or 'Grape shots'), were designed for close range defence. It was generally a cylindrical zinc or brass box with very thin walls, closed at its base and top by cheap means, and filled with lead bullets somewhat heavier than the ones of the shrapnel shells.

This ammunition was dismantled inside the gun tube by the discharge and propulsed its bullets load at point blank. In WW1, most of the guns needing this kind of ammo could use a conventional shrapnel shell to obtain a comparable effect by setting the fuze at range 'zero'

The canister shots were therefore rarely used during WW1, except for some specific applications, such as close-range fortresses defence guns or infantry guns.

The general organisation of such a weapon was pretty universal amongst the fighting countries. It can be explained taking as an example the high explosive shell ,of the French 75mm fieldgun. The shell body is a single piece forged steel piece, from the base to the igival head, with thicker wallthicknesses than the shrapnel shell, and pierced at its top by a threaded hole for fuze insertion. The shell weight was 5.300 kg, and it was filled with 850 g of Melinite explosive. Since this material was corroding the steel to form unstable components, the inner surfaces of the shell were protected with varnish or a tin layer, to avoid accidental explosions.

In some cases, for instance most of the German heavy caliber shells, the high explosive shells were an assembly of several seperate parts, the base being threaded on the cylindric / ogival part and bearing a base fuze. In some German high explosive shells of medium to light caliber, it was sometimes the head that could be threaded onto the body.

These high explosive shells effects were dreadful and could vary depending on the kind of fuze used (as seen in below section). The shell fragments produced by these ammunitions burst ranged from tiny particles able to penetrate deep inside the human body to big and sharp steel sections flying quick to dislocate men in pieces... When used with a delay fuze, the shell could explode underground and produce shell holes of every sizes, creating the characteristic lunar landscape of WW1 battlefield, still visible nowadays under the trees and bushes, one century later..

During the war years, the high explosive shells progressively replaced the shrapnell in the batteries, being able to provide all the needed missions by using the appropriate fuzes, including shrapnel-like inflight explosion.

Defective French high explosive 75mm shell. The organization is well visible with the fuze, the exploder, the thick walled steel body and the copper driving band.

Wartime scheme of the French 75mm high explosive shell.

High explosive shell fragment, coming from the shell head. The effects of such a sharp piece of steel flying at full speed on a human body are dreadful... (found in Artois)

Effects of a high explosive shell equipped with a percussion fuze without delay :

Effects of a high explosive shell equipped with a percussion fuze with delay :

The brutal deceleration of the fuze when hitting the target or the ground triggers its mechanism, burtsing the shell while it is penetrating the obstacle. A shell hole is created in the ground, and shell fragments are spread over the ground. 'Universal' use in antipersonnel or anti-entrenchment missions.

The brutal deceleration of the delay fuze when hitting the target or the ground triggers its mechanism, whose action is delayed for some seconds hundredths in order to make the shell burst instants after it penetrated the obstacle. A deep shell hole is created in the ground, and few shell fragments are spread over the ground. Specific use for shelters or entrenchments destruction.

Effects of a high explosive shell equipped with a superquick percussion :

Effects of a high explosive shell equipped with a time fuze :

The brutal deceleration of the superquick fuze (positioned ahead of the shell body) when hitting the target or the ground triggers its mechanism, burtsing the shell before it is penetrating the obstacle. A very small or no shell hole is created in the ground, but a big quantity of fragments are spread over the ground. Specific use in antipersonnel or barbwire destruction missions.

The time fuze triggers the shell burst inflight, the shell fragments are mostly projected perpendicularly to the trajectory. Specific use in antipersonnel missions, but more efficient than the shrapnell shell against enemies sheletred in deep trenches provided the explosion occurs just at their vertical.

The initial mission for which the perforation shells had been created was the armor piercing. Used with heavy caliber guns, they were the usual ammunition of the navy artillery for the destruction of steel hulls of ironclad ships.

This kind of shell had a thick and full hardened steel head body, and very thick steel walls. These characteristics gave it improved perforation properties in its target, a delay fuze (internal or base fuze) making it burst after it penetrates the armor.

This kind of concept was extended to the Army fighting onshore, for the destruction of reinforced concrete fortresses and shelters by heavy guns and howitzers, using both shock and mine effects, and later to the fieldguns dedicated to anti-tank fight.

Knowing that the wall thicknesses were considerably bigger, the explosive charge proportion was lower than high explosive shell in relation to the total weight (10 to 12% compared to 16 to 30%).The fuze was most of the time fixed through the shell base, eor inserted inside the shell itself, but never on the shell head. Like in high explosive heavy German shells, the shell bases were threaded at the rear of the single-piece huge shell body.

A special care was given to the shell aerodynamics, needed by the heavy weight and the wanted long ranges, giving way sometimes to the use of a thin steel plate hollow ogival head covering the real shell head.

Wartime scheme of French and Austrian super-heavy artillery shells with heavy wall thickness, full steel head and threaded base with base fuze hole.

The early XXth century conflicts and war tactice demonstrated before 1914 what would be evident just some months after august 1914, that is an increasing need of fieldguns ammunitions more powerful than the usual shrapnel shells, that prooved just good enough in percussion mode when hitting light shelters (bricks, wood, earth, etc...). In order to improve the shells destruction behavior, better explosive properties were needed. This is how the German Army designed a 'Universal shell' ('Einheitsgeschoss') before the war, and used it in the early stages of the conflict.

This shell was organized like a shrapnel shell but the resin mass usually surronding the bullets was replaced by TNT for a better explosive effect. Like many technical compromises, this projectile never gave full satisfaction neither as a shrapnel shell, nor as an explosive shelle, and was gradually abandoned. Moreover, it needed a very sophisticated time and percussion fuze ('KZ11' ou 'HZ05') able to order the multiple functions of the ammunition. The French arsenals designed a similar shell, as deceiving, named the 'Obus Robin'.

The tracer shells (in German 'Lichtspurgranate') were filled with a slow-burning composition (for instance a mixture of baryum nitrate and magnesium) or phosphorous and their head was pierced by holes letting the flames escape during the flight. These shells were leaving a smoke trace (or illuminated trace at night) behind them allowing to correct the aiming on aircraft targets, and had incendiary properties very useful against baloons and zeppelins.

Theincendiary shells (in German 'Brand Granate') were filled with slow but intense burning material, for instance tar impregnated tissue and gunpowder dust, able to burn about 2 minutes. These burning elements were dispersed meters away after the shell burst in every direction. One should note that the gunpowder explosive shells had pretty good incendiary properties.

The smoke shells (in German 'Rauchentwickler Granate'), looking like the explosive shells but filled with a phosphorous-based composition, ou sulfuric anhydrid, they emitted for some minutes after hittong the ground a dense smoke cloud designed to hide the friendly troops movements to the enemy.

The star shells (in German 'Leuchtgeschoss'), simple enveloppe enclosing fireworks 'stars' often made of magnesium base material, expulsed by the shell rear at the burst ordered by a time fuze, and descending slowly, often suspended to a small parachute, lighting the landscape and the enemy positions.

The gaz, suffocating or tear shells, were based on the same kind of design as the incendiary shells, but diepersed toxic or irritating material when hitting the ground. These shells were often made of a double envelope system : the inner envelope containing the agressive liquid could be made of glass or thin steel plate.

In other designs, the toxic material was contained inside a glass bottle that was broken by the shock of landing, simultaneously with the shell casing dismantling.

These shells were most often used with 'superquick' fuzes, so that the shell burst occurs over the ground.

See this excellent website for an extensive presentation of the WW1 gaz war history and material : 'La Guerre des Gaz'

Wartime scheme of the German 7.7cm 'Yellow cross' shell. Toxic material directly in contact with the shell walls.

Wartime scheme of the German 7.7cm 'Yellow cross' shell, with the toxic liquid contained into a glass bottle.

German gaz shell glass bottle container

The brutal deceleration of the superquick fuze (positioned ahead of the shell body) when hitting the target or the ground triggers its mechanism, burtsing the shell before it is penetrating the obstacle. The low power explosion breaks the weak envelope and the containers filled with the toxic materials and creates the gaz cloud.

The rapid evolution of the operations from a conventional field war to a trech war gave way to the quick and almost improvised development of trench artillery, whose mission was to send an as big as possible explosive charge to a short range, following an almost vertical ballistic curve. These various and numerous 'trench mortars', sometimes called 'Crapouillots' when French, 'Trench Mortars' when British, and 'Minenwerfers' or 'Ladungswerfers' when German, sent different ammunitions with a small muzzle speed.

These ammunitions being therefore less stressed than the usual shells by the weaker initial acceleration, these 'bombs' could be built with thin steel walls, and give the better part of their volume to considerable weights of powerful explosive charges that could represent up to 50 to 60 % of the total weight !

It is then easy to understand how such weapons were able to flatten tens of metres of trenches by a single hit, and destroy or terrorize their poor inhabitants.

Most of the trench artillery weapons tubes were not rifled, the inflight stabilty being then either random, or controlled by fins, efficient enough at small speeds. In these cases, the bomb was either inserted entirely with its body and fins inside the tube, or a cylindric tail welded to the bomb body was inserted inside the mortar bore (like for the French 58mm 'crapouillots' and their different ammunitions).

In other cases, like the powerful German reglementary minenwerfers, the trench mortars tubes were rifled like a conventional gun, and the ammunitions driving bands were premachined with the matching shapes, and introduced backwards by the gun muzzle.

This kind of weapons evoluated all along the war towards the infantry mortars, and the frontier with the grenade-launcher devices became often unclear. The final evolution brang the weapon to the famous British Stokes mortar, or to pneumatic mortars using compressed gaz for their grenade propulsion instead of explosives.

Different ammunitions of the French Trench mortars, with fins or driving bands.

Collection of German trench mortars, showing the extreme diversity of the weapons used in improvisation (upper picture), over the classical ammunitions of the reglementary and powerful Minenwerfers (lower picture).